双盘靶X光辐射光谱时空特性

在“星光－Ⅱ”激光装置上，利用三倍频激光辐照金双盘靶，研究Ｘ光辐射光谱时空特性。将４针孔透射光栅阵列和皮秒分幅相机结合，实现了Ｘ光辐射时间、空间、能谱三维联合测量，得到了双盘靶初级和次级辐射光谱结构，观测到Ｘ光辐射弛豫过程，并得到Ｎ带Ｏ带和零级光谱强度随时间和空间的变化特征、等离子体喷射二维空间分布、等离子体膨胀速率等重要结果。     

激光等离子体X光辐射非平衡特性实验研究

在ＬＦ－１１和ＬＦ－１２高功率激光装置上进行的实验中，设计了一些特定的激光束－金腔靶－探测器条件，创造了激光直接加热、准辐射加热和激光、Ｘ光混合加热三种物理条件，采用软Ｘ光透射光栅能谱时空分辨技术，测量了腔靶、缝靶和双孔靶等高分辨Ｘ光能谱，研究了激光等离子体Ｘ光辐射非平衡特性。     

X光焦斑测量方法研究

采用组合型诊断技术获取Ｘ光辐射时间、空间、能谱相互关联的３维信息,得到了Ｘ光焦斑随时间和随入射激光能量的变化关系,并观测到膨胀等离子体、探测器阈值、测量能区以及测试方位对Ｘ光焦斑测量带来的影响。     

腔靶X射线辐射特性实验研究

在上海“神光”装置上,对柱形腔靶X射线辐射的温度、光谱以及时间特性进行了实验研究,得到内爆区轴向温度随空间位置的变化特征。观测到腔内激光直接烧蚀靶物质产生的第一次X射线辐射和等离子体运动、汇聚形成的第二次X射线辐射,两次辐射的时间间隔为1.2ns。通过测量源区和内爆区X射线辐射空间能谱结构,结果表明源区X射线辐射能谱是非平衡的,而内爆区X射线辐射能谱近似为Planck谱。 关键词：     

中段目标的可见光辐射特性计算研究

中段目标的可见光辐射特性对目标的探测、跟踪与打击具有重要的指导意义。提出计算中段目标可见光辐射特性的方法,计算了目标表面的二向性反射,并考虑太阳的可见光辐射和云层背景反射太阳的可见光辐射情况下,计算了白天从同步卫星、低轨卫星和中轨卫星观测中段目标在可见光波段的辐射特性。研究结果表明：在可见光波段,目标对同步卫星辐射的光谱变化规律与太阳直射辐射的光谱变化一致,低轨卫星上观测目标的光谱辐射热流比同步卫星上观测的结果大3个数量级,中轨卫星上观测目标的光谱辐射热流比同步卫星上观测的结果大1个数量级。     

双色高频激光作用下原子低阶次谐波的理论研究

通过数值求解含时薛定谔方程,研究了高频双色激光脉冲与原子相互作用产生的光辐射.研究表明,光辐射谱中既有基频光的谐波,又可观测到谐波能量附近的多个频率的光辐射产生,且辐射的峰值强度随着入射激光强度的提高呈指数增强,相邻辐射频率差值为入射的两束激光脉冲频率差.     

绝对辐射计预测辐射电补偿的快速测量方法

绝对辐射计测量光辐射需要接收辐射和电定标两个阶段,这两个阶段都要使辐射计的接收腔达到热平衡才能比较它们的腔温响应．电定标其辐射量值。根据绝对辐射计接收腔在光入射(或电加热)时腔温升响应的指数变化规律,研究出在辐射入射腔之初就动态预测其功率．电加热补偿,使腔的温度住接收辐射和电定标阶段维持恒定的状态下．快速达到平衡进行测量的新方法。为世界辐射中心(PMOD／WRC)研制的两台太阳辐照绝对辐射计SIAR-2a和SIAR-2b采用了这种快速测量的厅法。斤在世界辐射中心进行一年半10000多次同世界标准(辐射计)组(WSG)一起同时观测太阳辐照度的比刘实验．结果表明其绝对辐射精度达到了0．08％．既保持了原有测量方法(慢速热平衡、测量时间长)的精度．又缩短了秒测量时间。     

纠缠相干态光场驱动下∧-型三能级原子的辐射谱

采用时间演化算符方法,研究∧-型=三能级原子与纠缠相干态光场共振相互作用的辐射谱.给出了辐射谱一般公式,并讨论在纠缠相干态光场驱动下的辐射频谱结构.结果表明,无论下能级简并与否纠缠相干态光场平均光子数很小时均出现拉比分裂,且强度随双模光场纠缠程度的增加而增加.当两下能级简并时,若两模场的平均光子数较小,辐射谱呈现对称多峰结构,若两模场的平均光子数较大,辐射谱呈现对称五峰结构.当两下能级非简并时,若两模场的平均光子数较小,辐射谱呈现对称多峰结构.若两模场的平均光子数较大,辐射谱呈现对称十峰结构.纠缠相干光与非纠缠相干光辐射谱的本质差别有两点:一是双模光场强量子关联导致纠缠度越强拉比峰强度越高;二是存在纠缠时由于两模场相干性导致辐射谱呈现对称多峰结构.     

二维三角晶格光子晶体波导的出射光集束传播

为了解决光子晶体波导出射端光场控制, 同时解决二维三角晶格光子晶体波导出射光辐射困难的问题。利用二维三角晶格光子晶体设计了一种新型光子晶体波导出射口结构。在二维三角晶格光子晶体波导出射端引入两个微腔, 通过光波与微腔发生共振, 形成类似于三个点光源干涉的出射光, 同时进一步提出波导出射端喇叭口干涉出射光定向辐射的设计。通过这种微腔喇叭口设计, 利用时域有限差分法分析结果表明光波实现很好的定向辐射, 并且辐射距离显著提高。     

双模腔场中两偶极相互作用原子的辐射谱

研究了双模腔场中两个偶极相互作用原子的辐射谱，详细讨论了双模腔场分别处于不同数态时的情形，发现其辐射谱具有如下特点：当两模腔场均处于真空态时，随着δ＝ｇ_a／ｇ的增加，辐射谱交替出现六峰、五峰结构，且在δ（＝３^－１／２）很小时就出现了非对称五峰结构，与单模双原子情形相比较，更为灵敏地反映出原子间的偶极相互作用；当一腔场为真空场，另一腔场为强场时，辐射谱显示出对称的六峰结构，任意两对称峰的间距与(2ｎ₂)^１／２ｇ成正比；当 关键词：     

X-ray gain in laser-produced carbon plasmas using double-layer targets

We investigate from a theoretical point of view the basic possibilities for the effect of ionizing radiation on the X-ray gain in recombining laser-produced plasmas, in particular with regard to recently performed experiments in which targets consisting of two different-material layers (double-layer targets) were used. We discuss an increase of the gain for the 3 2 transition in hydrogenic ions which is due to photoionization causing, mainly, a decrease of the Lyman- reabsorption and an increase of the population of higher levels. In our numerical simulations we consider single-material and double-layer targets, concentrating particularly on carbon and titanium. We obtain and discuss the time behaviour of the X-ray emission from the laser-produced plasma with regard to its application as pump radiation.     

管靶X射线辐射输运初步研究Ⅱ.实验测量与分析

从实验上研究了X射线在管靶中辐射输运情况.给出两种分解靶：源靶、输运靶.源靶可得到X射线输运的输入条件,输运靶是近似一维X射线输运管道,对其测量可得到输运的结果;给出两种分解靶由软X射线谱仪、平响应XRD和透射光栅谱仪(配X射线CCD)测量的结果,并对实验结果进行分析;最后对输运管道内的等离子体膨胀问题进行了讨论. 关键词：     

Dose estimation and shielding calculation for X-ray hazard at high intensity laser facilities

An ionizing radiation hazard produced from the interaction between high intensity lasers and solid targets has been observed. Laser-plasma interactions create "hot" electrons, which generate bremsstrahlung X-rays when they interact with ions in the target. However, up to now only limited studies have been conducted on this laser-induced radiological protection issue. In this paper, the physical process and characteristics of the interaction between high intensity lasers and solid targets are analyzed. The parameters of the radiation sources are discussed, including the energy conversion efficiency from laser to hot electrons, hot electron energy spectrum and electron temperature, and the bremsstrahlung X-ray energy spectrum produced by hot electrons. Based on this information, the X-ray dose generated with high-Z targets for laser intensities between 10¹⁴ and 10²⁰ W/cm² is estimated. The shielding effects of common shielding items such as the glass view port, aluminum chamber wall and concrete wall are also studied using the FLUKA Monte Carlo code. This study provides a reference for the dose estimation and the shielding design of high intensity laser facilities.     

高Z等离子体辐射的非平衡特性

 对激光直接加热和X光辐射加热Au等离子体的非平衡特性进行了实验研究，探讨了它们的物理机制。为此，提出了一种新型的锥盘靶结构，并在神光 II装置上进行了实验，结果表明：锥盘靶很好地避免了激光加热区的等离子体喷射和散射光对X光加热区的影响，改善了辐射加热场的干净性。对锥盘靶激光和辐射加热进行了模拟计算，所得结果与实验的结果符合较好。     

Measurement of intense X-Ray spectra: Methods based on CXR and Ross filter

The interaction between X-ray radiation and the material of secondary targets is simulated using GEANT4 for two methods of measurements of intense X-ray spectra. In the first case, characteristic X-ray radiation (CXR) from the secondary target to the back hemisphere is detected; in the second case, primary radiation passing through pairs of foils (a Ross filter) is registered. Using Ross filters and the CXR technique, the primary spectra of X-ray radiation are recovered. Two methods for recovery primary radiation spectra are compared.     

对激光等离子体中X射线的产生与辐射加热研究

利用一维辐射流体力学程序MULTI数值模拟研究了功率为1014Wcm2、脉冲宽度为300ps、波长为0.44μm的强激光辐照平面Au靶时产生X射线的过程,给出了X射线转换效率和能谱分布.通过将靶物质划分为对所产生的X射线光学薄的转化区和光学厚的再发射区,得到了作为黑体辐射热源的最佳靶厚度,并给出了辐射加热靶所产生的等离子体的密度和温度的空间分布. 关键词： 辐射流体力学 激光等离子体 X射线转换 辐射热波     

High-repetition-rate hard X-ray generation with sub-millijoule femtosecond laser pulses

Hard X-ray radiation is generated at 1-kHz repetition rate on metal targets using 30-fs sub-millijoule laser pulses. Spinning-disc targets of medium-Z (Ti, Cr, Fe, Ni, Cu, Zn and Mo) and high-Z (Ta) metals are investigated. For medium-Z targets, characteristic K-shell emission (K and K) is observed in the 4–20 keV energy range in addition to a broadband bremsstrahlung background. Whereas in former studies similar results have been obtained by applying laser pulses in the tens-to-hundreds-of-millijoules range, we observe characteristic X-ray generation even at applied pulse energies as low as 100 J. The well-defined emission wavelength, the high intensity and the high brightness of this radiation makes this source a promising tool for time-resolved experiments with high-repetition-rate (10 kHz) small-scale table-top laser systems . PACS 42.65.-k; 52.38.Ph; 52.50.Jm     

激光腔靶X射线面、体发射特性实验研究

介绍了在“神光”装置上进行的不同类型腔靶Ｘ射线面、体发射物理机制的实验研究。实验采用波长为１．０５３μｍ的激光,脉冲波形为高斯型,能量为５００一７００Ｊ／束,脉冲宽度为６００一１０００ｐｓ．典型靶由三个柱型腔组成,采取双束对打,两端的腔为吸收－转换区（源区）,中间腔为辐射加热的内爆区。给出源区及内爆区Ｘ射线面、体发射测量结果,并通过分析、估算给出面、体发射强度比。 关键词：     

Interference effects in the coherent X-ray radiation of relativistic electrons in two- and three-layer targets

A dynamic theory of the coherent X-ray radiation of relativistic electrons in “amorphous medium–single-crystal” and “amorphous medium–free-space–single-crystal” targets is developed. Expressions for the spectral-angular distributions of diffracted transition radiation (DTR), parametric X-ray radiation, and a term describing their interference are obtained. The spectral-angular density of the DTR is represented as a sum of terms describing the diffracted transition radiation from various boundaries and a term describing the interference of these components. Interference effects in the spectral-angular and angular densities of radiation are studied.